Conventional perpendicular magnetic recording (PMR) heads can be fabricated in a number of ways. FIG. 1 is a flow chart depicting a conventional method 10 for fabricating a PMR transducer using a conventional process. For simplicity, some steps are omitted. FIGS. 2-7 are diagrams a depicting conventional PMR transducer 50 as viewed from the air-bearing surface (ABS) during fabrication. The conventional PMR transducer 50 may be part of a coupled with a slider to form a PMR head. In addition, a read transducer (not shown) may be included to form a merged PMR head. For simplicity, only a portion of the conventional PMR transducer 50 is shown. The conventional method 10 is described in the context of the conventional PMR transducer 50.
The PMR pole layers and chemical mechanical planarization (CMP) stop layer are provided, via step 12. The PMR pole layers may include a seed layer and one or more layers forming the magnetic portion of the PMR pole. A hard mask is provided on the CMP stop layer, via step 14. The hard mask covers a portion of the PMR pole layers from which the conventional PMR pole is to be formed. FIG. 2 depicts the conventional PMR transducer 50 after step 14 is completed. Thus, the conventional PMR transducer 50 an underlayer 52 on which the PMR pole layer(s) 54 reside. A CMP stop layer 56 resides on the PMR pole layers 54. The hard mask 58 resides on a portion of the CMP stop layer 56 and PMR pole layers 54. The hard mask 58 may also reside on other portions (not shown) of the conventional PMR transducer 50. For example, during fabrication, the conventional PMR transducer 50 typically includes an anchor structure during fabrication as well as a yoke structure that is part of the conventional PMR transducer 50. The underlayer 52 may include aluminum oxide or other nonmagnetic material. The PMR pole layer(s) 54 include magnetic materials suitable for use in the conventional PMR transducer 50. The CMP stop layer 56 may include materials, such as diamond-like carbon (DLC), having a low removal rate for during a CMP. The hard mask 58 may include materials such as NiFe.
The conventional PMR pole is defined from the PMR pole layers 54, via step 16. Step 16 typically includes performing an ion mill and a pole trim using the hard mask 56 to expose the portion of the PMR pole layer(s) to be removed. FIG. 3 depicts the conventional PMR transducer 50 after step 16 is completed. Thus, the conventional PMR pole 54′ has been formed. In addition, only a portion of the CMP stop layer 56′ remains.
A conventional intermediate layer is provided, via step 18. The conventional intermediate layer is typically aluminum oxide that is blanket deposited on the conventional PMR transducer 50. FIG. 4 depicts the conventional PMR transducer 50 after step 18 has been performed. Thus, the conventional intermediate layer 60 has been formed. The conventional intermediate layer 60 covers the conventional PMR pole 54′, the CMP stop layer 56′, and the hard mask 58.
A CMP is performed to completely remove the hard mask 58, via step 20. Step 20 is configured to remove the hard mask 58 from substantially all of the structures on which the hard mask 58 resides. Thus, the hard mask 58 is substantially removed from the conventional PMR pole 54′ as well as other structures, such as the yoke (not shown) and anchor structures. FIG. 5 depicts the conventional PMR transducer 50 after step 20 is performed. Thus, a substantially planar surface formed by the top of the intermediate layer 60′ and the CMP stop layer 56′.
The CMP stop layer 56′ is removed, via step 22. FIG. 6 depicts the conventional PMR transducer 50 after step 22 is performed. Thus, the top surface is formed by portions of the intermediate layer 60′ and the conventional PMR pole 54′. A write gap is deposited on the PMR transducer 50 and a shield is provided, via steps 24 and 26, respectively. FIG. 7 depicts the conventional PMR transducer 50 after step 26 is performed. Thus, the write gap 62 and trailing shield 64 are shown. Also shown is a notch 63 in the shield 64 due to the topology of the conventional PMR transducer 50.
Although the conventional method 10 may provide the conventional PMR transducer 50, there may be drawbacks. In particular, as the critical dimensions of structures in the conventional PMR transducer 50 shrink to accommodate higher densities, tighter control may be desired for the structures in the conventional PMR transducer 50. Conventional methods, including the conventional method 10, may not provide the desired control over at least some portions of the conventional PMR transducer 50.
For example, some methods for forming the conventional PMR transducer 50 result in the top surface of the intermediate layer 60′ being at the same height as the top of the conventional PMR pole 54′. Such conventional methods may include those in which the conventional PMR pole 54′ is deposited into a trench rather than being defined by a milling process. In such a case, the notch 64 may be nonexistent. The method 10 may also be somewhat uncontrolled. For example, in some cases, removal of the hard mask 58 in step 20 removes a greater portion of the intermediate layer 60. FIGS. 8-9 depict a conventional PMR transducer 50′ in which this has occurred. The conventional PMR transducer 50′ is analogous to the conventional PMR transducer 50 and may be formed using the conventional method 10. Thus, the conventional PMR transducer 50′ includes underlayer 52′, conventional PMR pole 54″, intermediate layer 60″, and CMP stop layer 66″. Because a greater portion of the intermediate layer 60″ has been removed, the top surface of the intermediate layer 60″ is lower than the top of the conventional PMR pole 54″. Moreover, a portion of the PMR pole 54″ may be inadvertently removed. Thus, when the write gap 62′ and top shield 64′ are provided in steps 24 and 26, the notch 63′ is in the opposite direction from the notch 63. Consequently, conventional methods for fabricating the conventional PMR transducer 50 may result in a notch 63, no notch, or a notch 63′ in the reverse direction. Conventional methods for fabricating the conventional PMR transducer 50 may thus have relatively large variations in the conventional PMR transducer 50. Consequently, performance of the conventional PMR transducer 50/50′ may vary even when the same method 10 is used for fabricating the conventional PMR transducer 50/50′
Accordingly, what is needed is an improved method for fabricating a PMR transducer.